There are numerous situations where it is important to control light energy and light transmission. For example, in a xerographic reproduction system, such as a printer, digital copier or facsimile machine, light from a source must be modulated into a series of dots (on and off conditions of the light) to form the image which is to be reproduced. The actual reproduction to the final media (typically paper) is accomplished through a light-sensitive photoreceptor in the form of a rotating drum, or belt, onto which the modulated light image has been transmitted. The drum is electrostatically discharged at the place where the light dots have exposed the drum so that charged ink particles called toner, adhere to the drum at those places. This toner is then transferred to the paper to create the final reproduced image.
In common xerographic printer systems, the electrical signals are converted to light images by modulation of the light output of a laser that is in turn rastered across the drum by a rotating polygon mirror. The modulated signals are then applied to the rotating drum. This light modulation systems suffers from the problem that there are a large number of parts which must be in perfect optical alignment. Additionally, IR heating problems arise from the use of a laser light source. Another commonly used light source is the tungsten halogen light bulb.
In attempt to reduce the cost and complexity of such systems and improve print quality, it is desirable to provide a system which will maintain a reduced-heat environment. Accordingly, there is a need in the art for a printing system which generates less heat than today's systems which employ a halogen lamp, a CRT or a laser light source.
There is a further need in the art for such a system in which the light modulation system is a compact system in order to reduce to a minimum the printer size. These problems must be solved while maintaining high reliability through the use of solid state electronics and without establishing the need for complicated light transmission paths.